libstdc++
rc_string_base.h
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1 // Reference-counted versatile string base -*- C++ -*-
2 
3 // Copyright (C) 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10 
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15 
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19 
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24 
25 /** @file ext/rc_string_base.h
26  * This file is a GNU extension to the Standard C++ Library.
27  * This is an internal header file, included by other library headers.
28  * You should not attempt to use it directly.
29  */
30 
31 #ifndef _RC_STRING_BASE_H
32 #define _RC_STRING_BASE_H 1
33 
34 #include <ext/atomicity.h>
36 
37 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
38 
39  /**
40  * Documentation? What's that?
41  * Nathan Myers <ncm@cantrip.org>.
42  *
43  * A string looks like this:
44  *
45  * @code
46  * [_Rep]
47  * _M_length
48  * [__rc_string_base<char_type>] _M_capacity
49  * _M_dataplus _M_refcount
50  * _M_p ----------------> unnamed array of char_type
51  * @endcode
52  *
53  * Where the _M_p points to the first character in the string, and
54  * you cast it to a pointer-to-_Rep and subtract 1 to get a
55  * pointer to the header.
56  *
57  * This approach has the enormous advantage that a string object
58  * requires only one allocation. All the ugliness is confined
59  * within a single pair of inline functions, which each compile to
60  * a single "add" instruction: _Rep::_M_refdata(), and
61  * __rc_string_base::_M_rep(); and the allocation function which gets a
62  * block of raw bytes and with room enough and constructs a _Rep
63  * object at the front.
64  *
65  * The reason you want _M_data pointing to the character array and
66  * not the _Rep is so that the debugger can see the string
67  * contents. (Probably we should add a non-inline member to get
68  * the _Rep for the debugger to use, so users can check the actual
69  * string length.)
70  *
71  * Note that the _Rep object is a POD so that you can have a
72  * static "empty string" _Rep object already "constructed" before
73  * static constructors have run. The reference-count encoding is
74  * chosen so that a 0 indicates one reference, so you never try to
75  * destroy the empty-string _Rep object.
76  *
77  * All but the last paragraph is considered pretty conventional
78  * for a C++ string implementation.
79  */
80  template<typename _CharT, typename _Traits, typename _Alloc>
82  : protected __vstring_utility<_CharT, _Traits, _Alloc>
83  {
84  public:
85  typedef _Traits traits_type;
86  typedef typename _Traits::char_type value_type;
87  typedef _Alloc allocator_type;
88 
89  typedef __vstring_utility<_CharT, _Traits, _Alloc> _Util_Base;
90  typedef typename _Util_Base::_CharT_alloc_type _CharT_alloc_type;
91  typedef typename _CharT_alloc_type::size_type size_type;
92 
93  private:
94  // _Rep: string representation
95  // Invariants:
96  // 1. String really contains _M_length + 1 characters: due to 21.3.4
97  // must be kept null-terminated.
98  // 2. _M_capacity >= _M_length
99  // Allocated memory is always (_M_capacity + 1) * sizeof(_CharT).
100  // 3. _M_refcount has three states:
101  // -1: leaked, one reference, no ref-copies allowed, non-const.
102  // 0: one reference, non-const.
103  // n>0: n + 1 references, operations require a lock, const.
104  // 4. All fields == 0 is an empty string, given the extra storage
105  // beyond-the-end for a null terminator; thus, the shared
106  // empty string representation needs no constructor.
107  struct _Rep
108  {
109  union
110  {
111  struct
112  {
113  size_type _M_length;
114  size_type _M_capacity;
115  _Atomic_word _M_refcount;
116  } _M_info;
117 
118  // Only for alignment purposes.
119  _CharT _M_align;
120  };
121 
122  typedef typename _Alloc::template rebind<_Rep>::other _Rep_alloc_type;
123 
124  _CharT*
125  _M_refdata() throw()
126  { return reinterpret_cast<_CharT*>(this + 1); }
127 
128  _CharT*
129  _M_refcopy() throw()
130  {
131  __atomic_add_dispatch(&_M_info._M_refcount, 1);
132  return _M_refdata();
133  } // XXX MT
134 
135  void
136  _M_set_length(size_type __n)
137  {
138  _M_info._M_refcount = 0; // One reference.
139  _M_info._M_length = __n;
140  // grrr. (per 21.3.4)
141  // You cannot leave those LWG people alone for a second.
142  traits_type::assign(_M_refdata()[__n], _CharT());
143  }
144 
145  // Create & Destroy
146  static _Rep*
147  _S_create(size_type, size_type, const _Alloc&);
148 
149  void
150  _M_destroy(const _Alloc&) throw();
151 
152  _CharT*
153  _M_clone(const _Alloc&, size_type __res = 0);
154  };
155 
156  struct _Rep_empty
157  : public _Rep
158  {
159  _CharT _M_terminal;
160  };
161 
162  static _Rep_empty _S_empty_rep;
163 
164  // The maximum number of individual char_type elements of an
165  // individual string is determined by _S_max_size. This is the
166  // value that will be returned by max_size(). (Whereas npos
167  // is the maximum number of bytes the allocator can allocate.)
168  // If one was to divvy up the theoretical largest size string,
169  // with a terminating character and m _CharT elements, it'd
170  // look like this:
171  // npos = sizeof(_Rep) + (m * sizeof(_CharT)) + sizeof(_CharT)
172  // + sizeof(_Rep) - 1
173  // (NB: last two terms for rounding reasons, see _M_create below)
174  // Solving for m:
175  // m = ((npos - 2 * sizeof(_Rep) + 1) / sizeof(_CharT)) - 1
176  // In addition, this implementation halves this amount.
177  enum { _S_max_size = (((static_cast<size_type>(-1) - 2 * sizeof(_Rep)
178  + 1) / sizeof(_CharT)) - 1) / 2 };
179 
180  // Data Member (private):
181  mutable typename _Util_Base::template _Alloc_hider<_Alloc> _M_dataplus;
182 
183  void
184  _M_data(_CharT* __p)
185  { _M_dataplus._M_p = __p; }
186 
187  _Rep*
188  _M_rep() const
189  { return &((reinterpret_cast<_Rep*>(_M_data()))[-1]); }
190 
191  _CharT*
192  _M_grab(const _Alloc& __alloc) const
193  {
194  return (!_M_is_leaked() && _M_get_allocator() == __alloc)
195  ? _M_rep()->_M_refcopy() : _M_rep()->_M_clone(__alloc);
196  }
197 
198  void
199  _M_dispose()
200  {
201  if (__exchange_and_add_dispatch(&_M_rep()->_M_info._M_refcount,
202  -1) <= 0)
203  _M_rep()->_M_destroy(_M_get_allocator());
204  } // XXX MT
205 
206  bool
207  _M_is_leaked() const
208  { return _M_rep()->_M_info._M_refcount < 0; }
209 
210  void
211  _M_set_sharable()
212  { _M_rep()->_M_info._M_refcount = 0; }
213 
214  void
215  _M_leak_hard();
216 
217  // _S_construct_aux is used to implement the 21.3.1 para 15 which
218  // requires special behaviour if _InIterator is an integral type
219  template<typename _InIterator>
220  static _CharT*
221  _S_construct_aux(_InIterator __beg, _InIterator __end,
222  const _Alloc& __a, std::__false_type)
223  {
224  typedef typename iterator_traits<_InIterator>::iterator_category _Tag;
225  return _S_construct(__beg, __end, __a, _Tag());
226  }
227 
228  // _GLIBCXX_RESOLVE_LIB_DEFECTS
229  // 438. Ambiguity in the "do the right thing" clause
230  template<typename _Integer>
231  static _CharT*
232  _S_construct_aux(_Integer __beg, _Integer __end,
233  const _Alloc& __a, std::__true_type)
234  { return _S_construct(static_cast<size_type>(__beg), __end, __a); }
235 
236  template<typename _InIterator>
237  static _CharT*
238  _S_construct(_InIterator __beg, _InIterator __end, const _Alloc& __a)
239  {
240  typedef typename std::__is_integer<_InIterator>::__type _Integral;
241  return _S_construct_aux(__beg, __end, __a, _Integral());
242  }
243 
244  // For Input Iterators, used in istreambuf_iterators, etc.
245  template<typename _InIterator>
246  static _CharT*
247  _S_construct(_InIterator __beg, _InIterator __end, const _Alloc& __a,
249 
250  // For forward_iterators up to random_access_iterators, used for
251  // string::iterator, _CharT*, etc.
252  template<typename _FwdIterator>
253  static _CharT*
254  _S_construct(_FwdIterator __beg, _FwdIterator __end, const _Alloc& __a,
256 
257  static _CharT*
258  _S_construct(size_type __req, _CharT __c, const _Alloc& __a);
259 
260  public:
261  size_type
262  _M_max_size() const
263  { return size_type(_S_max_size); }
264 
265  _CharT*
266  _M_data() const
267  { return _M_dataplus._M_p; }
268 
269  size_type
270  _M_length() const
271  { return _M_rep()->_M_info._M_length; }
272 
273  size_type
274  _M_capacity() const
275  { return _M_rep()->_M_info._M_capacity; }
276 
277  bool
278  _M_is_shared() const
279  { return _M_rep()->_M_info._M_refcount > 0; }
280 
281  void
282  _M_set_leaked()
283  { _M_rep()->_M_info._M_refcount = -1; }
284 
285  void
286  _M_leak() // for use in begin() & non-const op[]
287  {
288  if (!_M_is_leaked())
289  _M_leak_hard();
290  }
291 
292  void
293  _M_set_length(size_type __n)
294  { _M_rep()->_M_set_length(__n); }
295 
297  : _M_dataplus(_S_empty_rep._M_refcopy()) { }
298 
299  __rc_string_base(const _Alloc& __a);
300 
301  __rc_string_base(const __rc_string_base& __rcs);
302 
303 #ifdef __GXX_EXPERIMENTAL_CXX0X__
305  : _M_dataplus(__rcs._M_get_allocator(), __rcs._M_data())
306  { __rcs._M_data(_S_empty_rep._M_refcopy()); }
307 #endif
308 
309  __rc_string_base(size_type __n, _CharT __c, const _Alloc& __a);
310 
311  template<typename _InputIterator>
312  __rc_string_base(_InputIterator __beg, _InputIterator __end,
313  const _Alloc& __a);
314 
316  { _M_dispose(); }
317 
318  allocator_type&
319  _M_get_allocator()
320  { return _M_dataplus; }
321 
322  const allocator_type&
323  _M_get_allocator() const
324  { return _M_dataplus; }
325 
326  void
327  _M_swap(__rc_string_base& __rcs);
328 
329  void
330  _M_assign(const __rc_string_base& __rcs);
331 
332  void
333  _M_reserve(size_type __res);
334 
335  void
336  _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
337  size_type __len2);
338 
339  void
340  _M_erase(size_type __pos, size_type __n);
341 
342  void
343  _M_clear()
344  { _M_erase(size_type(0), _M_length()); }
345 
346  bool
347  _M_compare(const __rc_string_base&) const
348  { return false; }
349  };
350 
351  template<typename _CharT, typename _Traits, typename _Alloc>
354 
355  template<typename _CharT, typename _Traits, typename _Alloc>
358  _S_create(size_type __capacity, size_type __old_capacity,
359  const _Alloc& __alloc)
360  {
361  // _GLIBCXX_RESOLVE_LIB_DEFECTS
362  // 83. String::npos vs. string::max_size()
363  if (__capacity > size_type(_S_max_size))
364  std::__throw_length_error(__N("__rc_string_base::_Rep::_S_create"));
365 
366  // The standard places no restriction on allocating more memory
367  // than is strictly needed within this layer at the moment or as
368  // requested by an explicit application call to reserve().
369 
370  // Many malloc implementations perform quite poorly when an
371  // application attempts to allocate memory in a stepwise fashion
372  // growing each allocation size by only 1 char. Additionally,
373  // it makes little sense to allocate less linear memory than the
374  // natural blocking size of the malloc implementation.
375  // Unfortunately, we would need a somewhat low-level calculation
376  // with tuned parameters to get this perfect for any particular
377  // malloc implementation. Fortunately, generalizations about
378  // common features seen among implementations seems to suffice.
379 
380  // __pagesize need not match the actual VM page size for good
381  // results in practice, thus we pick a common value on the low
382  // side. __malloc_header_size is an estimate of the amount of
383  // overhead per memory allocation (in practice seen N * sizeof
384  // (void*) where N is 0, 2 or 4). According to folklore,
385  // picking this value on the high side is better than
386  // low-balling it (especially when this algorithm is used with
387  // malloc implementations that allocate memory blocks rounded up
388  // to a size which is a power of 2).
389  const size_type __pagesize = 4096;
390  const size_type __malloc_header_size = 4 * sizeof(void*);
391 
392  // The below implements an exponential growth policy, necessary to
393  // meet amortized linear time requirements of the library: see
394  // http://gcc.gnu.org/ml/libstdc++/2001-07/msg00085.html.
395  if (__capacity > __old_capacity && __capacity < 2 * __old_capacity)
396  {
397  __capacity = 2 * __old_capacity;
398  // Never allocate a string bigger than _S_max_size.
399  if (__capacity > size_type(_S_max_size))
400  __capacity = size_type(_S_max_size);
401  }
402 
403  // NB: Need an array of char_type[__capacity], plus a terminating
404  // null char_type() element, plus enough for the _Rep data structure,
405  // plus sizeof(_Rep) - 1 to upper round to a size multiple of
406  // sizeof(_Rep).
407  // Whew. Seemingly so needy, yet so elemental.
408  size_type __size = ((__capacity + 1) * sizeof(_CharT)
409  + 2 * sizeof(_Rep) - 1);
410 
411  const size_type __adj_size = __size + __malloc_header_size;
412  if (__adj_size > __pagesize && __capacity > __old_capacity)
413  {
414  const size_type __extra = __pagesize - __adj_size % __pagesize;
415  __capacity += __extra / sizeof(_CharT);
416  if (__capacity > size_type(_S_max_size))
417  __capacity = size_type(_S_max_size);
418  __size = (__capacity + 1) * sizeof(_CharT) + 2 * sizeof(_Rep) - 1;
419  }
420 
421  // NB: Might throw, but no worries about a leak, mate: _Rep()
422  // does not throw.
423  _Rep* __place = _Rep_alloc_type(__alloc).allocate(__size / sizeof(_Rep));
424  _Rep* __p = new (__place) _Rep;
425  __p->_M_info._M_capacity = __capacity;
426  return __p;
427  }
428 
429  template<typename _CharT, typename _Traits, typename _Alloc>
430  void
431  __rc_string_base<_CharT, _Traits, _Alloc>::_Rep::
432  _M_destroy(const _Alloc& __a) throw ()
433  {
434  const size_type __size = ((_M_info._M_capacity + 1) * sizeof(_CharT)
435  + 2 * sizeof(_Rep) - 1);
436  _Rep_alloc_type(__a).deallocate(this, __size / sizeof(_Rep));
437  }
438 
439  template<typename _CharT, typename _Traits, typename _Alloc>
440  _CharT*
441  __rc_string_base<_CharT, _Traits, _Alloc>::_Rep::
442  _M_clone(const _Alloc& __alloc, size_type __res)
443  {
444  // Requested capacity of the clone.
445  const size_type __requested_cap = _M_info._M_length + __res;
446  _Rep* __r = _Rep::_S_create(__requested_cap, _M_info._M_capacity,
447  __alloc);
448 
449  if (_M_info._M_length)
450  _S_copy(__r->_M_refdata(), _M_refdata(), _M_info._M_length);
451 
452  __r->_M_set_length(_M_info._M_length);
453  return __r->_M_refdata();
454  }
455 
456  template<typename _CharT, typename _Traits, typename _Alloc>
457  __rc_string_base<_CharT, _Traits, _Alloc>::
458  __rc_string_base(const _Alloc& __a)
459  : _M_dataplus(__a, _S_construct(size_type(), _CharT(), __a)) { }
460 
461  template<typename _CharT, typename _Traits, typename _Alloc>
462  __rc_string_base<_CharT, _Traits, _Alloc>::
463  __rc_string_base(const __rc_string_base& __rcs)
464  : _M_dataplus(__rcs._M_get_allocator(),
465  __rcs._M_grab(__rcs._M_get_allocator())) { }
466 
467  template<typename _CharT, typename _Traits, typename _Alloc>
468  __rc_string_base<_CharT, _Traits, _Alloc>::
469  __rc_string_base(size_type __n, _CharT __c, const _Alloc& __a)
470  : _M_dataplus(__a, _S_construct(__n, __c, __a)) { }
471 
472  template<typename _CharT, typename _Traits, typename _Alloc>
473  template<typename _InputIterator>
474  __rc_string_base<_CharT, _Traits, _Alloc>::
475  __rc_string_base(_InputIterator __beg, _InputIterator __end,
476  const _Alloc& __a)
477  : _M_dataplus(__a, _S_construct(__beg, __end, __a)) { }
478 
479  template<typename _CharT, typename _Traits, typename _Alloc>
480  void
481  __rc_string_base<_CharT, _Traits, _Alloc>::
482  _M_leak_hard()
483  {
484  if (_M_is_shared())
485  _M_erase(0, 0);
486  _M_set_leaked();
487  }
488 
489  // NB: This is the special case for Input Iterators, used in
490  // istreambuf_iterators, etc.
491  // Input Iterators have a cost structure very different from
492  // pointers, calling for a different coding style.
493  template<typename _CharT, typename _Traits, typename _Alloc>
494  template<typename _InIterator>
495  _CharT*
496  __rc_string_base<_CharT, _Traits, _Alloc>::
497  _S_construct(_InIterator __beg, _InIterator __end, const _Alloc& __a,
499  {
500  if (__beg == __end && __a == _Alloc())
501  return _S_empty_rep._M_refcopy();
502 
503  // Avoid reallocation for common case.
504  _CharT __buf[128];
505  size_type __len = 0;
506  while (__beg != __end && __len < sizeof(__buf) / sizeof(_CharT))
507  {
508  __buf[__len++] = *__beg;
509  ++__beg;
510  }
511  _Rep* __r = _Rep::_S_create(__len, size_type(0), __a);
512  _S_copy(__r->_M_refdata(), __buf, __len);
513  __try
514  {
515  while (__beg != __end)
516  {
517  if (__len == __r->_M_info._M_capacity)
518  {
519  // Allocate more space.
520  _Rep* __another = _Rep::_S_create(__len + 1, __len, __a);
521  _S_copy(__another->_M_refdata(), __r->_M_refdata(), __len);
522  __r->_M_destroy(__a);
523  __r = __another;
524  }
525  __r->_M_refdata()[__len++] = *__beg;
526  ++__beg;
527  }
528  }
529  __catch(...)
530  {
531  __r->_M_destroy(__a);
532  __throw_exception_again;
533  }
534  __r->_M_set_length(__len);
535  return __r->_M_refdata();
536  }
537 
538  template<typename _CharT, typename _Traits, typename _Alloc>
539  template<typename _InIterator>
540  _CharT*
541  __rc_string_base<_CharT, _Traits, _Alloc>::
542  _S_construct(_InIterator __beg, _InIterator __end, const _Alloc& __a,
544  {
545  if (__beg == __end && __a == _Alloc())
546  return _S_empty_rep._M_refcopy();
547 
548  // NB: Not required, but considered best practice.
549  if (__builtin_expect(__is_null_pointer(__beg) && __beg != __end, 0))
550  std::__throw_logic_error(__N("__rc_string_base::"
551  "_S_construct NULL not valid"));
552 
553  const size_type __dnew = static_cast<size_type>(std::distance(__beg,
554  __end));
555  // Check for out_of_range and length_error exceptions.
556  _Rep* __r = _Rep::_S_create(__dnew, size_type(0), __a);
557  __try
558  { _S_copy_chars(__r->_M_refdata(), __beg, __end); }
559  __catch(...)
560  {
561  __r->_M_destroy(__a);
562  __throw_exception_again;
563  }
564  __r->_M_set_length(__dnew);
565  return __r->_M_refdata();
566  }
567 
568  template<typename _CharT, typename _Traits, typename _Alloc>
569  _CharT*
570  __rc_string_base<_CharT, _Traits, _Alloc>::
571  _S_construct(size_type __n, _CharT __c, const _Alloc& __a)
572  {
573  if (__n == 0 && __a == _Alloc())
574  return _S_empty_rep._M_refcopy();
575 
576  // Check for out_of_range and length_error exceptions.
577  _Rep* __r = _Rep::_S_create(__n, size_type(0), __a);
578  if (__n)
579  _S_assign(__r->_M_refdata(), __n, __c);
580 
581  __r->_M_set_length(__n);
582  return __r->_M_refdata();
583  }
584 
585  template<typename _CharT, typename _Traits, typename _Alloc>
586  void
587  __rc_string_base<_CharT, _Traits, _Alloc>::
588  _M_swap(__rc_string_base& __rcs)
589  {
590  if (_M_is_leaked())
591  _M_set_sharable();
592  if (__rcs._M_is_leaked())
593  __rcs._M_set_sharable();
594 
595  _CharT* __tmp = _M_data();
596  _M_data(__rcs._M_data());
597  __rcs._M_data(__tmp);
598 
599  // _GLIBCXX_RESOLVE_LIB_DEFECTS
600  // 431. Swapping containers with unequal allocators.
601  std::__alloc_swap<allocator_type>::_S_do_it(_M_get_allocator(),
602  __rcs._M_get_allocator());
603  }
604 
605  template<typename _CharT, typename _Traits, typename _Alloc>
606  void
607  __rc_string_base<_CharT, _Traits, _Alloc>::
608  _M_assign(const __rc_string_base& __rcs)
609  {
610  if (_M_rep() != __rcs._M_rep())
611  {
612  _CharT* __tmp = __rcs._M_grab(_M_get_allocator());
613  _M_dispose();
614  _M_data(__tmp);
615  }
616  }
617 
618  template<typename _CharT, typename _Traits, typename _Alloc>
619  void
620  __rc_string_base<_CharT, _Traits, _Alloc>::
621  _M_reserve(size_type __res)
622  {
623  // Make sure we don't shrink below the current size.
624  if (__res < _M_length())
625  __res = _M_length();
626 
627  if (__res != _M_capacity() || _M_is_shared())
628  {
629  _CharT* __tmp = _M_rep()->_M_clone(_M_get_allocator(),
630  __res - _M_length());
631  _M_dispose();
632  _M_data(__tmp);
633  }
634  }
635 
636  template<typename _CharT, typename _Traits, typename _Alloc>
637  void
638  __rc_string_base<_CharT, _Traits, _Alloc>::
639  _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
640  size_type __len2)
641  {
642  const size_type __how_much = _M_length() - __pos - __len1;
643 
644  _Rep* __r = _Rep::_S_create(_M_length() + __len2 - __len1,
645  _M_capacity(), _M_get_allocator());
646 
647  if (__pos)
648  _S_copy(__r->_M_refdata(), _M_data(), __pos);
649  if (__s && __len2)
650  _S_copy(__r->_M_refdata() + __pos, __s, __len2);
651  if (__how_much)
652  _S_copy(__r->_M_refdata() + __pos + __len2,
653  _M_data() + __pos + __len1, __how_much);
654 
655  _M_dispose();
656  _M_data(__r->_M_refdata());
657  }
658 
659  template<typename _CharT, typename _Traits, typename _Alloc>
660  void
661  __rc_string_base<_CharT, _Traits, _Alloc>::
662  _M_erase(size_type __pos, size_type __n)
663  {
664  const size_type __new_size = _M_length() - __n;
665  const size_type __how_much = _M_length() - __pos - __n;
666 
667  if (_M_is_shared())
668  {
669  // Must reallocate.
670  _Rep* __r = _Rep::_S_create(__new_size, _M_capacity(),
671  _M_get_allocator());
672 
673  if (__pos)
674  _S_copy(__r->_M_refdata(), _M_data(), __pos);
675  if (__how_much)
676  _S_copy(__r->_M_refdata() + __pos,
677  _M_data() + __pos + __n, __how_much);
678 
679  _M_dispose();
680  _M_data(__r->_M_refdata());
681  }
682  else if (__how_much && __n)
683  {
684  // Work in-place.
685  _S_move(_M_data() + __pos,
686  _M_data() + __pos + __n, __how_much);
687  }
688 
689  _M_rep()->_M_set_length(__new_size);
690  }
691 
692  template<>
693  inline bool
694  __rc_string_base<char, std::char_traits<char>,
696  _M_compare(const __rc_string_base& __rcs) const
697  {
698  if (_M_rep() == __rcs._M_rep())
699  return true;
700  return false;
701  }
702 
703 #ifdef _GLIBCXX_USE_WCHAR_T
704  template<>
705  inline bool
706  __rc_string_base<wchar_t, std::char_traits<wchar_t>,
708  _M_compare(const __rc_string_base& __rcs) const
709  {
710  if (_M_rep() == __rcs._M_rep())
711  return true;
712  return false;
713  }
714 #endif
715 
716 _GLIBCXX_END_NAMESPACE
717 
718 #endif /* _RC_STRING_BASE_H */
The "standard" allocator, as per [20.4].Further details: http://gcc.gnu.org/onlinedocs/libstdc++/manu...
Definition: allocator.h:60
Forward iterators support a superset of input iterator operations.
GNU extensions for public use.
Marking input iterators.
iterator_traits< _InputIterator >::difference_type distance(_InputIterator __first, _InputIterator __last)
A generalization of pointer arithmetic.